Emitter for trace samples of nickel isotope analysis and its application in thermal ionization mass spectrometry

Abstract

An emitter for nickel isotope analysis of trace samples, its preparation and application are provided, wherein: the emitter is a zirconium hydrogen phosphate emitter; and the zirconium hydrogen phosphate emitter specifically comprises a zirconium hydrogen phosphate suspension and phosphoric acid solution as an auxiliary material. To prepare the zirconium hydrogen phosphate suspension, the zirconium hydrogen phosphate powder must be washed alternately with hydrochloric acid and high-purity water 3 to 4 times to reduce the sample loading blank. The application specifically relates to analytical method, specifically using zirconium hydrogen phosphate suspension as a high-sensitivity emitter to enhance the ionization efficiency of nickel samples, while using phosphoric acid solution to assist ionization, and using high-purity tungsten filament as the sample carrier to determine trace nickel isotope method.

What is claimed is: 
     
         1 . An emitter for trace samples of nickel isotope analysis, wherein:
 the emitter is a zirconium hydrogen phosphate emitter; and   the zirconium hydrogen phosphate specifically comprises a zirconium hydrogen phosphate suspension and a phosphoric acid solution as an auxiliary material.   
     
     
         2 . The emitter for trace samples of nickel isotope analysis, as recited in  claim 1 , wherein the zirconium hydrogen phosphate suspension is prepared by the following process: first alternately washing the high-purity zirconium hydrogen phosphate powder by hydrochloric acid and high-purity deionized water 3 to 4 times to reduce a sample loading blank; then adding deionized water to the treated zirconium hydrogen phosphate powder to prepare zirconium hydrogen phosphate suspension with a certain concentration. 
     
     
         3 . The emitter for trace samples of nickel isotope analysis, as recited in  claim 2 , wherein a concentration of the zirconium hydrogen phosphate suspension is converted according to a dosage of the zirconium hydrogen phosphate emitter required for each analysis and a loading amount of the zirconium hydrogen phosphate suspension, specifically, the dosage of the high-purity zirconium hydrogen phosphate powder required for each analysis, It is 30±0.2 micrograms, and the loading size of the zirconium phosphate suspension is 1 to 3 μL, so the concentration of the zirconium hydrogen phosphate suspension is at a range of 10 to 30 mg/mL. 
     
     
         4 . The emitter for trace samples of nickel isotope analysis, as recited in  claim 2 , wherein a purity of the high-purity zirconium phosphate powder is greater than 99.9%; and a particle size of the high-purity zirconium phosphate powder is less than 75 μm. 
     
     
         5 . A method for preparing an emitter for trace samples of nickel isotope analysis, wherein the emitter is a zirconium hydrogen phosphate emitter; and the zirconium hydrogen phosphate emitter specifically comprises a zirconium hydrogen phosphate suspension and phosphoric acid solution as an auxiliary material;
 (1) a preparation method of the zirconium hydrogen phosphate suspension comprising steps of:   S1: pre-treating zirconium hydrogen phosphate, comprising:   S11: weighing the high-purity zirconium hydrogen phosphate powder and placing in a teflon vial, adding hydrochloric acid in proportion, closing the teflon vial and placing on a hot plate at 80-100 degrees for 1 to 2 hours, shaking the vial during heating time, and cleaning the zirconium hydrogen phosphate with hydrochloric acid powder to reduce the loading blank;   S12: then, cooling to room temperature, taking out an upper layer of hydrochloric acid solution, adding high-purity deionized water, closing again and shaking the container for 3 to 4 minutes, standing still for layering, and sucking out the supernatant again;   S13: repeating the cleaning process of steps S11 and S12 for 3 to 4 times, and finally obtaining a precipitation phase, which is the pretreated zirconium hydrogen phosphate;   S2: weighing the zirconium hydrogen phosphate pretreated in step S13 and adding deionized water to prepare a zirconium hydrogen phosphate suspension of a certain concentration; wherein the concentration of the zirconium hydrogen phosphate suspension is based on the dose of zirconium hydrogen phosphate emitter required for each analysis and the loading volume of zirconium hydrogen phosphate suspension; specifically, the dosage of high-purity zirconium hydrogen phosphate powder required for each analysis is 30±0.2 μg, and the loading volume of zirconium hydrogen phosphate suspension is 1-3 μL; the concentration of the zirconium hydrogen phosphate suspension is 10-30 mg/mL;   (2) preparing phosphoric acid solution weighing the concentrated phosphoric acid solution, adding deionized water in proportion to prepare a phosphoric acid solution with a concentration at a range of 0.8-1.0 mol/L.   
     
     
         6 . The method as recited in  claim 5 , wherein in step S11, a concentration of hydrochloric acid for cleaning is 2 to 4 mol/L, and an amount of hydrochloric acid for cleaning is 1 ml per (30±0.2 mg) high-purity zirconium hydrogen phosphate powder;
 in step S12, an amount of high-purity deionized water used for cleaning is 1 ml per (30±0.2 mg) high-purity zirconium hydrogen phosphate powder. 
 
     
     
         7 . A method for determining nickel isotopes of trace samples, which is characterized in adopting zirconium hydrogen phosphate suspension as a high-sensitivity emitter to enhance the ionization efficiency of nickel samples, and meanwhile adopting phosphoric acid solution to assist ionization, and adopting high-purity tungsten filament as a sample carrier to determine nickel isotopes. 
     
     
         8 . The method for determining nickel isotopes in trace samples as recited in  claim 7 , which is characterized in specifically comprising steps of:
 (1) taking an appropriate amount of the emitter composed of zirconium hydrogen phosphate suspension and phosphoric acid solution and coating on the surface of the high-purity tungsten filament; after the emitter evaporates to dryness, loading the nickel sample on the surface of the filament, and tuning the current to 2.2 amperes and evaporating to dryness, then continuing to increase the filament current until the filament turns a dull red glow for 3 to 5 seconds, and then returning the current to zero;   (2) installing the sample magazine with nickel sample into the thermal ionization mass spectrometer, and using the thermal ionization mass spectrometer to obtain high-precision nickel isotope data; wherein the temperature of the filament is at a range of 1030-1130° C. during the measurement.   
     
     
         9 . The method as recited in  claim 8 , wherein step (1) The coating process of the emitter is as follows:
 taking 1-2 μL of phosphoric acid solution with a concentration of 0.8-1.0 mol/L and applying on a surface of high-purity tungsten filament, tuning the filament current to evaporate the phosphoric acid solution to dryness, and then taking 1-3 μL of a certain concentration of zirconium hydrogen phosphate suspension to cover on the evaporated phosphoric acid coating, after the zirconium hydrogen phosphate suspension is evaporated to dryness, loading the nickel sample on the surface of the W filament.   
     
     
         10 . The method, as recited in  claim 8 , wherein in step (1), an amount of nickel sample is at a range of 200-1000 ng.